Interface DangoResponse

Trailers are only be emitted if the message is chunked encoded. If not, the trailer will be silently discarded.

HTTP requires the Trailer header to be sent to emit trailers, with a list of header fields in its value, e.g.

message.writeHead(200, { 'Content-Type': 'text/plain',
                         'Trailer': 'Content-MD5' });
message.write(fileData);
message.addTrailers({ 'Content-MD5': '7895bf4b8828b55ceaf47747b4bca667' });
message.end();

Attempting to set a header field name or value that contains invalid characters will result in a TypeError being thrown.

Note: calling res.set() after res.append() will reset the previously-set header value.

Examples:

res.type('.html');
res.type('html');
res.type('json');
res.type('application/json');
res.type('png');

Options:

• maxAge max-age in milliseconds, converted to expires
• signed sign the cookie
• path defaults to "/"

Examples:

// "Remember Me" for 15 minutes res.cookie('rememberme', '1', { expires: new Date(Date.now() + 900000), httpOnly: true });

// save as above res.cookie('rememberme', '1', { maxAge: 900000, httpOnly: true })

The primary intent of writable.cork() is to accommodate a situation in which several small chunks are written to the stream in rapid succession. Instead of immediately forwarding them to the underlying destination, writable.cork()buffers all the chunks until writable.uncork() is called, which will pass them all to writable._writev(), if present. This prevents a head-of-line blocking situation where data is being buffered while waiting for the first small chunk to be processed. However, use of writable.cork() without implementingwritable._writev() may have an adverse effect on throughput.

See also: writable.uncork(), writable._writev().

Once destroy() has been called any further calls will be a no-op and no further errors except from _destroy() may be emitted as 'error'.

Implementors should not override this method, but instead implement writable._destroy().

Optionally providing an alternate attachment filename, and optional callback fn(err). The callback is invoked when the data transfer is complete, or when an error has ocurred. Be sure to check res.headersSent if you plan to respond.

The optional options argument passes through to the underlying res.sendFile() call, and takes the exact same parameters.

This method uses res.sendfile().

Calling the write method after calling end will raise an error.

// Write 'hello, ' and then end with 'world!'.
const fs = require('fs');
const file = fs.createWriteStream('example.txt');
file.write('hello, ');
file.end('world!');
// Writing more now is not allowed!

const EventEmitter = require('events');
const myEE = new EventEmitter();
myEE.on('foo', () => {});
myEE.on('bar', () => {});

const sym = Symbol('symbol');
myEE.on(sym, () => {});

console.log(myEE.eventNames());
// Prints: [ 'foo', 'bar', Symbol(symbol) ]

For efficiency reason, Node.js normally buffers the message headers until outgoingMessage.end() is called or the first chunk of message data is written. It then tries to pack the headers and data into a single TCP packet.

It is usually desired (it saves a TCP round-trip), but not when the first data is not sent until possibly much later. outgoingMessage.flushHeaders()bypasses the optimization and kickstarts the request.

This method uses req.accepted, an array of acceptable types ordered by their quality values. When "Accept" is not present the first callback is invoked, otherwise the first match is used. When no match is performed the server responds with 406 "Not Acceptable".

Content-Type is set for you, however if you choose you may alter this within the callback using res.type() or res.set('Content-Type', ...).

res.format({ 'text/plain': function(){ res.send('hey'); },

 'text/html': function(){
   res.send('<p>hey</p>');
 },

 'appliation/json': function(){
   res.send({ message: 'hey' });
 }

});

In addition to canonicalized MIME types you may also use extnames mapped to these types:

res.format({ text: function(){ res.send('hey'); },

 html: function(){
   res.send('<p>hey</p>');
 },

 json: function(){
   res.send({ message: 'hey' });
 }

});

By default Express passes an Error with a .status of 406 to next(err) if a match is not made. If you provide a .default callback it will be invoked instead.

The object returned by the outgoingMessage.getHeaders() method does not prototypically inherit from the JavaScript Object. This means that typical Object methods such as obj.toString(), obj.hasOwnProperty(), and others are not defined and will not work.

outgoingMessage.setHeader('Foo', 'bar');
outgoingMessage.setHeader('Set-Cookie', ['foo=bar', 'bar=baz']);

const headers = outgoingMessage.getHeaders();
// headers === { foo: 'bar', 'set-cookie': ['foo=bar', 'bar=baz'] }

const hasContentType = outgoingMessage.hasHeader('content-type');

Examples:

res.links({ next: 'http://api.example.com/users?page=2', last: 'http://api.example.com/users?page=5' });

server.on('connection', (stream) => {
  console.log('someone connected!');
});
console.log(util.inspect(server.listeners('connection')));
// Prints: [ [Function] ]

The given url can also be the name of a mapped url, for example by default express supports "back" which redirects to the Referrer or Referer headers or "/".

Examples:

res.location('/foo/bar').; res.location('http://example.com'); res.location('../login'); // /blog/post/1 -> /blog/login

Mounting:

When an application is mounted and res.location() is given a path that does not lead with "/" it becomes relative to the mount-point. For example if the application is mounted at "/blog", the following would become "/blog/login".

 res.location('login');

While the leading slash would result in a location of "/login":

 res.location('/login');

const emitter = new EventEmitter();
emitter.once('log', () => console.log('log once'));

// Returns a new Array with a function `onceWrapper` which has a property
// `listener` which contains the original listener bound above
const listeners = emitter.rawListeners('log');
const logFnWrapper = listeners[0];

// Logs "log once" to the console and does not unbind the `once` event
logFnWrapper.listener();

// Logs "log once" to the console and removes the listener
logFnWrapper();

emitter.on('log', () => console.log('log persistently'));
// Will return a new Array with a single function bound by `.on()` above
const newListeners = emitter.rawListeners('log');

// Logs "log persistently" twice
newListeners[0]();
emitter.emit('log');

The resulting url is determined by res.location(), so it will play nicely with mounted apps, relative paths, "back" etc.

Examples:

res.redirect('/foo/bar'); res.redirect('http://example.com'); res.redirect(301, 'http://example.com'); res.redirect('http://example.com', 301); res.redirect('../login'); // /blog/post/1 -> /blog/login

It is bad practice to remove listeners added elsewhere in the code, particularly when the EventEmitter instance was created by some other component or module (e.g. sockets or file streams).

Returns a reference to the EventEmitter, so that calls can be chained.

outgoingMessage.removeHeader('Content-Encoding');

Options:

• cache boolean hinting to the engine it should cache
• filename filename of the view being rendered

Automatically sets the Content-Type response header field. The callback fn(err) is invoked when the transfer is complete or when an error occurs. Be sure to check res.headersSent if you wish to attempt responding, as the header and some data may have already been transferred.

Options:

• maxAge defaulting to 0 (can be string converted by ms)
• root root directory for relative filenames
• headers object of headers to serve with file
• dotfiles serve dotfiles, defaulting to false; can be "allow" to send them

Other options are passed along to send.

Examples:

The following example illustrates how res.sendFile() may be used as an alternative for the static() middleware for dynamic situations. The code backing res.sendFile() is actually the same code, so HTTP cache support etc is identical.

app.get('/user/:uid/photos/:file', function(req, res){
  var uid = req.params.uid
    , file = req.params.file;

  req.user.mayViewFilesFrom(uid, function(yes){
    if (yes) {
      res.sendFile('/uploads/' + uid + '/' + file);
    } else {
      res.send(403, 'Sorry! you cant see that.');
    }
  });
});

Examples:

res.set('Foo', ['bar', 'baz']); res.set('Accept', 'application/json'); res.set({ Accept: 'text/plain', 'X-API-Key': 'tobi' });

Aliased as res.header().

Returns a reference to the EventEmitter, so that calls can be chained.

Examples:

res.type('.html');
res.type('html');
res.type('json');
res.type('application/json');
res.type('png');

When using writable.cork() and writable.uncork() to manage the buffering of writes to a stream, it is recommended that calls to writable.uncork() be deferred using process.nextTick(). Doing so allows batching of allwritable.write() calls that occur within a given Node.js event loop phase.

stream.cork();
stream.write('some ');
stream.write('data ');
process.nextTick(() => stream.uncork());

If the writable.cork() method is called multiple times on a stream, the same number of calls to writable.uncork() must be called to flush the buffered data.

stream.cork();
stream.write('some ');
stream.cork();
stream.write('data ');
process.nextTick(() => {
  stream.uncork();
  // The data will not be flushed until uncork() is called a second time.
  stream.uncork();
});

See also: writable.cork().

res.vary('User-Agent').render('docs');

The return value is true if the internal buffer is less than thehighWaterMark configured when the stream was created after admitting chunk. If false is returned, further attempts to write data to the stream should stop until the 'drain' event is emitted.

While a stream is not draining, calls to write() will buffer chunk, and return false. Once all currently buffered chunks are drained (accepted for delivery by the operating system), the 'drain' event will be emitted. It is recommended that once write() returns false, no more chunks be written until the 'drain' event is emitted. While calling write() on a stream that is not draining is allowed, Node.js will buffer all written chunks until maximum memory usage occurs, at which point it will abort unconditionally. Even before it aborts, high memory usage will cause poor garbage collector performance and high RSS (which is not typically released back to the system, even after the memory is no longer required). Since TCP sockets may never drain if the remote peer does not read the data, writing a socket that is not draining may lead to a remotely exploitable vulnerability.

Writing data while the stream is not draining is particularly problematic for a Transform, because the Transform streams are paused by default until they are piped or a 'data' or 'readable' event handler is added.

If the data to be written can be generated or fetched on demand, it is recommended to encapsulate the logic into a Readable and use pipe. However, if calling write() is preferred, it is possible to respect backpressure and avoid memory issues using the 'drain' event:

function write(data, cb) {
  if (!stream.write(data)) {
    stream.once('drain', cb);
  } else {
    process.nextTick(cb);
  }
}

// Wait for cb to be called before doing any other write.
write('hello', () => {
  console.log('Write completed, do more writes now.');
});

A Writable stream in object mode will always ignore the encoding argument.

headers may be an Array where the keys and values are in the same list. It is not a list of tuples. So, the even-numbered offsets are key values, and the odd-numbered offsets are the associated values. The array is in the same format as request.rawHeaders.

Returns a reference to the ServerResponse, so that calls can be chained.

const body = 'hello world';
response
  .writeHead(200, {
    'Content-Length': Buffer.byteLength(body),
    'Content-Type': 'text/plain'
  })
  .end(body);

This method must only be called once on a message and it must be called before response.end() is called.

If response.write() or response.end() are called before calling this, the implicit/mutable headers will be calculated and call this function.

When headers have been set with response.setHeader(), they will be merged with any headers passed to response.writeHead(), with the headers passed to response.writeHead() given precedence.

If this method is called and response.setHeader() has not been called, it will directly write the supplied header values onto the network channel without caching internally, and the response.getHeader() on the header will not yield the expected result. If progressive population of headers is desired with potential future retrieval and modification, use response.setHeader() instead.

// Returns content-type = text/plain
const server = http.createServer((req, res) => {
  res.setHeader('Content-Type', 'text/html');
  res.setHeader('X-Foo', 'bar');
  res.writeHead(200, { 'Content-Type': 'text/plain' });
  res.end('ok');
});

Content-Length is given in bytes, not characters. Use Buffer.byteLength() to determine the length of the body in bytes. Node.js does not check whether Content-Length and the length of the body which has been transmitted are equal or not.

Attempting to set a header field name or value that contains invalid characters will result in a TypeError being thrown.